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Possible reasons for using kites to kill gazelles are comprehensively reviewed in this article. Even though they are now well inventoried and documented, desert kites are still not well understood, as exemplified by the recurrent controversies about their function and dating. According to the dominant view, kites were hunting structures used to drive and to mass kill large herds of wild ungulates, particularly gazelles. Although kites were intensively used during the Early Bronze Age, some of them could have been built and used before that. Beyond these issues, the cultural and socioeconomic aspects of the kites phenomenon are even less understood, and therefore, we focus on changing reasons for the long-lasting use of kites as hunting devices. We contend that the reasons why they were used during the period of utilization for hunting gazelles changed, in most cases, in response to socioeconomic development. It is hypothesized, for example, that, as a result of urban development, kites may have been increasingly (but not exclusively) used to kill gazelles to trade their products with urban communities and farmers, even though they had other uses as well which are also considered. The main hypothesis presented in this article enables diverse opinions about the types of uses and reasons for utilizing desert kites to be reconciled, including in particular varied reasons given in the literature about why they were used for killing gazelles.

The purpose of this study is to achieve lower and lower temperature as infrared sensors works faster and better used for space application. For getting good quality images from space, the infrared sensors are need to keep in cryogenic temperature. Cooling to cryogenic temperatures is necessary for space-borne sensors used for space applications. Infrared sensors work faster or better at lower temperatures. It is the need for time to achieve lower and lower temperatures.

This study presents the investigation of the critical Stirling cryocooler parameters that influence the cold end temperature. In the paper, the design approach, the dimensions gained through thermal analysis, experimental procedure and testing results are discussed.

The effect of parameters such as multilayer insulation, helium gas charging pressure, compressor input voltage and cooling load was investigated. The performance of gold-plated and aluminized multilayer insulation is checked. The tests were done with multilayer insulation covering inside and outside the Perspex cover.

By using aluminized multilayer insulation inside and outside the Perspex cover, the improvement of 16 K in cool-down temperature was achieved. The cryocooler is charged with helium gas. The pressure varies between 14 and 18 bar. The optimum cooling is obtained for 17 bar gas pressure. The piston stroke increased as the compressor voltage increased, resulting in total helium gas compression. The optimum cool-down temperature was attained at 85 V.

The cryocooler is designed to achieve the cool-down temperature of 2 W cooling load at 100 K. The lowest cool-down temperature recorded was 105 K at a 2 W cooling load. Multilayer insulation is the major item that keeps the thermal radiation from the sun from reaching the copper tip.

This paper is a description of an automated overhead warehouse system, developed to store car seat covers and then to feed them to the Renault car assembly plant at Palencia (Spain). It is based on trolleys moved through monorails and stored in accumulation bars (or monorails) by gravity, having to fulfil space and shape constraints, low retrieval time requirements, etc. This paper presents the decision process and the solutions adopted in this project to overcome the constraints and to fulfil the specifications. Also, a simulation tool integrated in an object‐ oriented designing framework is presented. It has been developed to support the decision‐making process, especially at the very beginning of the project.

The purpose of this paper is to introduce a novel methodology that has the capability of finding symmetrical and nonsymmetrical solutions in complex design domains without additional tuning when changing the design domain. These go from an academic design domain to a practical one.

Various crossovers operators are applied over the same representation using a genetic algorithm for truss structural optimization cases where literature solutions have a tendency to forced symmetry in order to find an optimal design with fewer iterations. Continuous‐discrete representations were cross‐bred by a uniform‐sbx simultaneous crossover, called zygote crossover. Specialized mutations operations are proposed to generate localized changes to improve the solution according with the design domain.

Design solutions found were lighter and stiffer when comparing against cases reported in current literature and in engineering practice. Also these solutions were found in fewer iterations.

The cases solved herein are complex and are a challenge for any optimization routine however practical design limitations are observed in the sense of out plane stability. Further comparisons cases are required in order to generate a less adjusted design, this is because the greenhouse solution had to be stiffened with out of plane bars to give it enough lateral stability.

Continuous‐discrete representations were cross‐bred by a uniform‐sbx simultaneous crossover, called natural crossover. Specialized mutations operations are proposed to generate localized changes to improve the solution according with the design domain. This scheme along with a less restrictive environment allows a wider exploration of search space.

Purpose — To develop methodologies to evaluate search engines according to an individual's preference in an easy and reliable manner, and to formulate user-oriented metrics to compare freshness and duplication in search results.

Design/methodology/approach — A personalised evaluation model for comparing search engines is designed as a hierarchy of weighted parameters. These commonly found search engine features and performance measures are given quantitative and qualitative ratings by an individual user. Furthermore, three performance measurement metrics are formulated and presented as histograms for visual inspection. A methodology is introduced to quantitatively compare and recognise the different histogram patterns within the context of search engine performance.

Findings — Precision and recall are the fundamental measures used in many search engine evaluations due to their simplicity, fairness and reliability. Most recent evaluation models are user oriented and focus on relevance issues. Identifiable statistical patterns are found in performance measures of search engines.

Research limitations/implications — The specific parameters used in the evaluation model could be further refined. A larger scale user study would confirm the validity and usefulness of the model. The three performance measures presented give a reasonably informative overview of the characteristics of a search engine. However, additional performance parameters and their resulting statistical patterns would make the methodology more valuable to the users.

Practical implications — The easy-to-use personalised search engine evaluation model can be tailored to an individual's preference and needs simply by changing the weights and modifying the features considered. A user is able to get an idea of the characteristics of a search engine quickly using the quantitative measure of histogram patterns that represent the search performance metrics introduced.

Originality/value — The presented work is considered original as one of the first search engine evaluation models that can be personalised. This enables a Web searcher to choose an appropriate search engine for his/her needs and hence finding the right information in the shortest time with the least effort.

The purpose of this study is to understand the functional properties of ball valve in a compressible flow and simulation of experimental data collection of ball valve, was completely simulated.

Equations are solved according to finite volume and simplified algorithms. By measuring the flow parameters, including pressure and temperature at different points in the simulation circuit, flow coefficients and localized drop in the valve were determined in different openness cases of test valve and compared with experimental results. Determining a graph for flow coefficient variations in terms of the percentage of openness of the valve is very effective on the flow control as well as on optimizing its cross-section.

In the supersonic flow, flow coefficients and local drops of the valve are dependent on several parameters, including fluid flow rate. Flow coefficient graphs at different angles of the test valve show that by increasing the valve opening angle, the flow coefficient increases so that it reaches from 1.72 m³/h at a 30° angle to 46.29 m³/h at a 80° angle. It should be noted that these values in the experimental test were obtained 1.53 m³/h and 49.68 m³/h, respectively, and the percentage difference of these values by simulation was obtained for the angle of 30 degrees 11.7% and for the angle of 80°, about 7% per hour at an angle of 80°. Also, the coefficients of localized loss at different angles of test valve show that by increasing the angle of opening of the valve, the amount of localized loss decreases, so that the average value of 1515.2 in the angle of 30° reaches 1.9 at an angle of 80°. The percentage difference of these values by simulation, for the angle of 30° and 3.5% for the angle of 80°, was about 11.1%.

Determining a graph for flow coefficient variations versus the percentage of openness of the valve is very effective on the flow control as well as on optimizing its cross-section. In the supersonic flow, flow coefficients and local drop coefficients of the valve are dependent on several parameters, including fluid flow rate.

The purpose of this paper is to investigate the autoclave-pump pressured water distribution system. Pressured water is used in many manufacturing processes, as a raw material or as a service fluid for different applications.

The performances and the total installation costs of such systems are strongly related to its design and to its decision variables definition. The authors first identify the independent variables (i.e. the decision variables) and the dependent variables of the system and, second, propose a techno-economic mathematical method able to determine its minimum installation cost with an integrated approach.

The trade-off between the autoclave installation costs versus the pump installation costs is demonstrated. A sensitive analysis of the cost of the system as function of its decision variables has been performed to propose a practical graphical analysis tools to proper design the integrated pump-autoclave pressured water distribution system.

Many previous researches focus only on the pump system optimization or in the tank system optimization without an integrated approach. The wide utilization in industry of the autoclave-pump pressured water distribution system together with the lack of similar contributions in this area enforces the value of this research.

The purpose of this paper is to characterize and evaluate a new 3D‐printing process based on Poly(methyl methacrylate) (PMMA).

A benchmark part and standard parts were designed, printed by a 3D‐printer and characterized.

3D printed PMMA parts have a tensile strength of 2.91 MPa and a modulus of elasticity of 223 MPa. The mechanical properties can be improved by infiltrations with epoxy (tensile strength: 26.6 MPa, modulus of elasticity: 1,190 MPa). The surface quality of the parts can be improved by infiltration with wax for usage as lost models. The minimum feature size is 0.3 mm.

The PMMA‐based 3D printing process can be used for manufacturing concept models, functional parts and lost models for investment casting.

This is the first paper investigating a PMMA‐based 3D printing process.

Monitoring and diagnosis of fault cases for squirrel cage induction motors can be implemented using the multiple coupled circuit model. However, the identification of the associated model parameters for a specific machine is problematic. Up to now, the main options are measurement and test procedures or the use of finite element method analyses. However, these approaches are very costly and not suitable for use in an industrial application. The purpose of this paper is a practical parameter identification based on optimization methods and a comparison of different algorithms for this task.

Population-based metaheuristics are used to determine the parameters for the multiple coupled circuit model. For this purpose, a search space for the required parameters is defined without an elaborate analytical approach. Subsequently, a genetic algorithm, the differential evolution algorithm and particle swarm optimization are tested and compared. The algorithms use the weighted mean squared error (MSE) between the real measured data of stator currents as well as speed and the simulation results of the model as a fitness function.

The results of the parameter identification show that the applied methodology generally works and all three optimization algorithms fulfill the task. The differential evolution algorithm performs best, with a weighted MSE of 2.62, the lowest error after 1,000 simulations. In addition, this algorithm achieves the lowest overall error of all algorithms after only 740 simulations. The determined parameters do not completely match the parameters of the real machine, but still result in a very good reproduction of the dynamic behavior of the induction motor with squirrel cage.

The value of the presented method lies in the application of condition-based maintenance of electric drives in the industry, which is performed based on the multiple coupled circuit model. With a parameterized model, various healthy as well as faulty states can be calculated and thus, in the future, monitoring and diagnosis of faults of the respective motor can be performed. Essential for this, however, are the parameters adapted to the respective machine. With the described method, an automated parameter identification can be realized without great effort as a basis for an intelligent and condition-oriented maintenance.

The purpose of this paper is the selection and arrangement of turbochargers set for internal combustion engine which could keep engine power in an altitude of up to 12.2 km above sea level.

In the current research, the target engine, a one-dimensional four-stroke 1,600 cc piston engine has been simulated and the manufacturer’ results have been validated. Depending on engine size, three proper types of Garret turbochargers GT30, GT25 and GT20 were selected for this engine. Then, the engine and a combination of two turbochargers have been modeled one-dimensionally. A control system was used for regulation of different pressure ratios between the two turbochargers.

The parametric analysis shows that using the combination of GT20, GT30 turbochargers with a properly controlled pressure ratio leads to a constant output power with little changes at different altitudes which enable achieving an altitude of 12.2 km for the target engine.

Adaptation of the internal combustion engine with a twin turbocharger using one-dimensional modeling.

The one-dimensional analysis provided an overall picture of the effective performance of turbochargers functioning in different altitudes and loads. It presents a new method for adopting of turbochargers set with internal combustion engines for propulsion medium-altitude aircraft.